AI: address review on PR #469

backend/app/models/post_implication.rb

@@ -8,6 +8,7 @@ class PostImplication < ApplicationRecord
   validates :parent_post_id, presence: true
 
   validate :parent_post_mustnt_be_itself
+  validate :parent_post_mustnt_create_cycle
 
   private
 
@@ -16,4 +17,24 @@ class PostImplication < ApplicationRecord
       errors.add :parent_post_id, '親投稿に同じ投稿を設定することはできません．'
     end
   end
+
+  def parent_post_mustnt_create_cycle
+    return if post_id.blank? || parent_post_id.blank?
+    return if errors[:parent_post_id].present?
+
+    ancestor_ids = Set.new
+    frontier_ids = [parent_post_id]
+
+    until frontier_ids.empty?
+      if frontier_ids.include?(post_id)
+        errors.add :parent_post_id, :invalid
+        return
+      end
+
+      ancestor_ids.merge(frontier_ids)
+      frontier_ids = PostImplication.where(post_id: frontier_ids)
+          .distinct.pluck(:parent_post_id)
+          .reject { ancestor_ids.include?(_1) }
+    end
+  end
 end

backend/spec/models/post_implication_spec.rb

@@ -48,4 +48,47 @@ RSpec.describe PostImplication, type: :model do
     expect(duplicate).not_to be_valid
     expect(duplicate.errors[:post_id]).to be_present
   end
+
+  it 'rejects a parent that would create a two-post cycle' do
+    described_class.create!(post: post_record, parent_post:)
+
+    implication = described_class.new(
+        post: parent_post, parent_post: post_record)
+
+    expect(implication).not_to be_valid
+    expect(implication.errors.of_kind?(:parent_post_id, :invalid)).to be true
+  end
+
+  it 'rejects a parent that would create a three-post cycle' do
+    ancestor_post = create(:post)
+    described_class.create!(post: post_record, parent_post:)
+    described_class.create!(post: parent_post, parent_post: ancestor_post)
+
+    implication = described_class.new(
+        post: ancestor_post, parent_post: post_record)
+
+    expect(implication).not_to be_valid
+    expect(implication.errors.of_kind?(:parent_post_id, :invalid)).to be true
+  end
+
+  it 'allows a parent with an ancestor when no cycle would result' do
+    ancestor_post = create(:post)
+    described_class.create!(post: parent_post, parent_post: ancestor_post)
+
+    implication = described_class.new(post: post_record, parent_post:)
+
+    expect(implication).to be_valid
+  end
+
+  it 'terminates when existing ancestors already contain a cycle' do
+    ancestor_post = create(:post)
+    described_class.create!(post: parent_post, parent_post: ancestor_post)
+    legacy_implication = described_class.new(
+        post: ancestor_post, parent_post:)
+    legacy_implication.save!(validate: false)
+
+    implication = described_class.new(post: post_record, parent_post:)
+
+    expect(implication).to be_valid
+  end
 end

frontend/src/components/PostFormTagsArea.tsx

@@ -36,13 +36,10 @@ const replaceToken = (value: string, start: number, end: number, text: string) =
 type Props = Omit<ComponentPropsWithoutRef<'textarea'>, 'value' | 'onChange' | 'onBlur'> & {
     tags:     string
     setTags:  (tags: string) => void
-    label?:   ReactNode
     errors?:  ReactNode[] }
 
 
-const PostFormTagsArea: FC<Props> = (
-    { tags, setTags, label: fieldLabel, errors, ...rest },
-) => {
+const PostFormTagsArea: FC<Props> = ({ tags, setTags, errors, ...rest }) => {
   const { label } = useUITranslation ('navigation')
   const locale = useLocale ()
   const ref = useRef<HTMLTextAreaElement> (null)
@@ -120,10 +117,7 @@ const PostFormTagsArea: FC<Props> = (
   }, [locale])
 
   return (
-      <FormField
-	  className="relative w-full"
-	  label={fieldLabel ?? label ('tags')}
-	  messages={errors}>
+      <FormField className="relative w-full" label={label ('tags')} messages={errors}>
 	{({ describedBy, invalid }) => (
 	    <>
 	      <TextArea

frontend/src/pages/tags/NicoTagListPage.test.tsx

@@ -162,13 +162,12 @@ describe ('NicoTagListPage', () => {
     })
   })
 
-  it ('saves links after completing the tag at the cursor', async () => {
+  it ('updates links from a tag card', async () => {
     api.apiGet
       .mockResolvedValueOnce ({
         tags:  [buildNicoTag ({ id: 7, name: 'nico:source' })],
         count: 1,
       })
-      .mockResolvedValueOnce ([buildTag ({ id: 8, name: '連携先', postCount: 3 })])
       .mockResolvedValueOnce ({
         tags: [
           buildNicoTag ({
@@ -184,24 +183,8 @@ describe ('NicoTagListPage', () => {
     renderPage ()
 
     fireEvent.click (await screen.findByRole ('button', { name: '編集' }))
-    const textarea = screen.getByLabelText ('連携する広場タグ')
-    fireEvent.change (textarea, { target: { value: '既存 連携\n後続' } })
-    fireEvent.focus (textarea)
-    fireEvent.select (textarea, {
-	target: { selectionStart: 4, selectionEnd: 4 } })
-
-    await waitFor (() => {
-      expect (api.apiGet).toHaveBeenCalledWith (
-	  '/tags/autocomplete',
-	  { locale: 'ja', params: { q: '連携', nico: '0' },
-	    signal: expect.any (AbortSignal) })
-    })
-    fireEvent.mouseDown (await screen.findByText ('連携先'))
-
-    expect (textarea).toHaveValue ('既存 連携先 \n後続')
-    await waitFor (() => {
-      expect ((textarea as HTMLTextAreaElement).selectionStart).toBe (7)
-      expect ((textarea as HTMLTextAreaElement).selectionEnd).toBe (7)
+    fireEvent.change (screen.getByLabelText ('連携する広場タグ'), {
+      target: { value: '連携先' },
     })
     fireEvent.click (screen.getByRole ('button', { name: '保存' }))
 
@@ -212,8 +195,6 @@ describe ('NicoTagListPage', () => {
           { locale: 'ja', headers: { 'Content-Type': 'multipart/form-data' } },
       )
     })
-    const payload = api.apiPut.mock.calls[0][1] as FormData
-    expect (payload.get ('tags')).toBe ('既存 連携先 \n後続')
     expect (await screen.findByText ('1 件')).toBeInTheDocument ()
   })
 

frontend/src/pages/tags/NicoTagListPage.tsx

@@ -6,10 +6,11 @@ import { useLocation } from 'react-router-dom'
 import { useLocale, useLocaleNavigate } from '@/lib/useLocale'
 import TagLink from '@/components/TagLink'
 import SortHeader from '@/components/SortHeader'
-import PostFormTagsArea from '@/components/PostFormTagsArea'
+import FieldError from '@/components/common/FieldError'
 import FormField from '@/components/common/FormField'
 import PageTitle from '@/components/common/PageTitle'
 import Pagination from '@/components/common/Pagination'
+import TextArea from '@/components/common/TextArea'
 import useDialogue from '@/lib/dialogues/useDialogue'
 import MainArea from '@/components/layout/MainArea'
 import { toast } from '@/components/ui/use-toast'
@@ -356,18 +357,21 @@ const NicoTagListPage: FC<Props> = ({ user }) => {
 					       dark:bg-rose-950/30">
 				  <td colSpan={editable ? 5 : 4} className="p-3">
 				    <div className="space-y-2">
-				      <PostFormTagsArea
+				      <label htmlFor={`nico-links-${ tag.id }`}
+					     className="block text-sm font-semibold">
+					{label ('nico.tagsToLink')}
+				      </label>
+				      <TextArea
 					  id={`nico-links-${ tag.id }`}
-					  label={label ('nico.tagsToLink')}
-					  aria-label={message ('nico.tagsToLink').text}
-					  tags={rawTags[tag.id] ?? ''}
-					  errors={errors}
+					  value={rawTags[tag.id] ?? ''}
+					  invalid={(errorsByTagId[tag.id] ?? []).length > 0}
 					  className="min-h-24 resize-y"
 					  placeholder={message ('nico.tagsPlaceholder').text}
 					  lang={message ('nico.tagsPlaceholder').language}
-					  setTags={value => setRawTags (rawTags => ({
+					  onChange={e => setRawTags (rawTags => ({
 					      ...rawTags,
-					      [tag.id]: value}))}/>
+					      [tag.id]: e.target.value}))}/>
+				      <FieldError messages={errors}/>
 				      <div className="flex justify-end gap-2">
 					<button
 					    type="button"